Patent GB-684517-A (GB)
Title: Improvements in hydraulic operating systems for ironing machines
IPC: D06F71/06
Filed: 1950-07-27
Abstract: 684,517. Ironing-presses. BRITISH THOMSON-HOUSTON CO., Ltd. July 27, 1950. [Aug. 5, 1949] No. 18795/50. Class 138 (ii). [Also in Group XXIX] In an ironing-machine comprising a buck 11 adapted for linear movement, a co-operating shoe 12 mounted on a carriage 14 for rocking movement, hydraulic means for actuating the buck 11 and shoe 12, and means for delaying movement of the buck until the shoe has substantially reached its operating position, means for generating the hydraulic pressure is accommodated within a main hydraulic cylinder 17 which serves for operating the buck. The carriage 14 is pivoted at 15 to the cylinder 17 which contains a piston 27 to one end of which the buck 11 is fixed. The piston 27 has rings 28, 29 and houses a motor (not shown) which drives a shaft 26 carrying an impeller 25. Piston ring 29 is carried by a composite piston head including a plate 30 from which extends a nozzle valve 31 adapted to co-operate with an outflow port 32. The cylinder 17 contains a light oil which under rest conditions reaches to a level L in Fig. 4. Oil reaches the impeller through side wall openings 38 and central openings 40, 42, and is discharged through the nozzle valve 31 and a passage 44 leading to a cylinder 24. This cylinder 24 contains a piston 51 whose piston rod 53 is pivotally connected to the carriage 14 by a suitable yoke 54. Fluid pressure thus moves the carriage 14 and shoe 12 to operating position this movement being terminated by the engagement of a stop 55 with an adjustable abutment 56. Full oil pressure then reacts against the small effective area of nozzle valve 31 to raise the piston 27 and the buck 11. On release of a foot switch the impeller stops and the buck piston is moved downwardly by gravity and a spring 58. The shoe 12 is returned by means of a pair of coil springs 52, 62 within the cylinder 24. Spring 62 is heavier and shorter than spring 52 and comes into operation only towards the end of the upward movement of the shoe 12. A supplementary flow passage 66 opens into the cylinder 24 at spaced ports 68, 70 and into a chamber 57 at 67. The ports 68, 70 are so spaced that when the piston 51 reaches its upper limit of work travel, port 68 is covered and port 70 either wholly or substantially uncovered. The passage 66 provides a low resistance path for any oil which may leak past the valve 31 and thus prevents the generation of sufficient pressure to raise the piston 27. Any oil entering the cylinder 24 above the piston 51 will be returned through an upper port 72 as the piston reaches its uppermost position. The circulation path afforded by the passage 66 and port 72 enables the operator to manually stop either of the pistons 27, 51 in midflight. The effective area of the valve 31 may be made so small that the buck piston 27 will not rise until the shoe piston 51 reaches its uppermost limit when fluid will pass through port 70 and passage 66 to chamber 57 to exert pressure against the large area of piston 27 and unseat the valve 31. The speed of movement of the carriage 14 may be limited by including a variable resistance in the impeller motor circuit, this resistance being cut out near the end of travel of the carriage by a shunt circuit controlled by a normally open switch 77 having a plunger 80 engaged by a projection 81 on the carriage as it nears its operating position. Thus the carriage rises slowly and the buck comes up quickly to apply ironing pressure. Speed control may alternatively be provided by means of an adjustment screw 44a (Fig. 9) which restricts the size of an orifice 33b leading to the flow passage 44. The simple nozzle valve 31 is replaced by a ported sleeve valve 31a which may be of sufficient length to remain in its seating during the whole movement of the buck 11. One or more ports 31b will be progressively exposed thus materially increasing the effective oil flow within the cylinder 17 and therefore the speed of movement of the buck.